According to scientists, children who grow up in messy homes are at lower risk of having a reaction to irritants like pollen and dog dander. In fact, a study published in the Journal of Allergy and Clinical Immunology in June found that Amish children were much less likely than other children to develop allergies and asthma.

The reason, says Dr. Richard Gallo, a professor at the University of California, San Diego, has to do with exposure and building up resistance. "It’s a change in your allergic set point," he said. "So being too clean can lead you to have a high allergic set point that will overreact to the environment."

Still, experts say this doesn't mean that we should abandon good hygiene. Instead, people should exercise judgment and rigorously clean only when exposed to dangerous bacteria.

"My advice is that some hygiene is good, too much is bad,” said Gallo. "In many cases you have to use common sense. You’re in a situation where you’re likely to be exposed to pathogens—germs that could cause disease—it’s a better idea to use sanitizers to remove them."